Templat aplikasi Pro Camera

Build a single-file mobile web app (index.html with inline CSS/JS) for Android WebView.

The app: Pro Camera — a full-screen camera app whose shutter, flip, flash, timer and grid buttons are HTML drawn over the native preview. Native camera under your HTML controls: flip, flash, timer, grid, gallery save and share.

Requirements:
- Mobile-first, touch-friendly UI (min 44px tap targets), works in portrait, supports light and dark mode.
- Use <meta name="viewport" content="width=device-width, initial-scale=1, viewport-fit=cover"> and pad for env(safe-area-inset-*).
- Must work fully offline: no CDN or external scripts, fonts or images; persist data in localStorage.

The page runs inside an Android app that injects a native bridge as window.FreeApp. Available APIs:
- FreeApp.camera.start(opts?: {facing?: 'back' | 'front', element?: string | Element /* place the preview over this element */, behind?: boolean /* draw under a transparent page so HTML controls float on top */}): Promise<{facing}>
- FreeApp.camera.capture(opts?: {maxSize?: number, quality?: number, mirror?: boolean}): Promise<{dataUrl, facing}> — still photo from the running preview
- FreeApp.camera.switch(): Promise<{facing}>; FreeApp.camera.torch(on: boolean): boolean; FreeApp.camera.stop(): void; FreeApp.camera.isOpen(): boolean
- FreeApp.saveToGallery(dataUrl: string, fileName?: string): Promise<{uri}> — saves an image to Photos
- FreeApp.shareFile(fileName: string, mimeType: string, base64OrDataUrl: string): boolean — share a real file
- FreeApp.toast(message: string): void — short native toast

Rules for the bridge:
- Always guard calls with `window.FreeApp &&` (or `if (window.FreeApp) { … }`) and provide a browser fallback so the page also works in a normal browser.
- The bridge may be injected after your script runs: do native setup inside `window.addEventListener('freeappready', …)` and also run it immediately if window.FreeApp already exists.
- Do not use alert/confirm for normal feedback; prefer FreeApp.toast when available.

Return the complete index.html in one code block.

My idea: [DESCRIBE YOUR APP IDEA HERE]